EPDM systems have their own set of pros and cons. The system does offer good ultraviolet, ozone, and weather reistance. However, it is vulnerable to fats and oils. Exposure to these cause the membrane to weaken and swell. EPDM also lacks halogen atoms. Halogen atoms are excellent fire retardants and found in PVC membrane roofs. (Griffin & Fricklas, 2006)
EPDM requires a significant amount of field-seaming. This is when the strips of the membrane are joined together to cover the roof. The area in which the sheets join is called a "seam." The seaming is the critial part of EPDM application. Solvent-based adhesives are used along with an elastometric sealant in most applications. Lap seam failure is very common with EPDM roofs. The chemical inertness which is good for ultraviolet resistance, makes the membrane hard to "wet" with the adhesvie and a strong steam diffcult to form. The surfaces to be adheared must be clean. Again, this is critical and hard to obtain due to the difficulty in wetting the membrane. This is true for both pressure-sensitive tapes and adhesive methods. For an improperly adhered seam, problems can quickly escalate as chemical aging and thermal-cycling weaken the seam even more and open it for leaks (Griffin & Fricklas, 2006). Many EPDM roofs need to have the seams resealed after 5-8 years.
Shrinkage (briding, tenting, contraction) are also common problems, occurring frequently at parpet walls, terminations, and flashings. While not limited just to EPDM roofing systems, ponding water is a concern, and voids many manufacturer warranties (Griffin & Fricklas, 2006).
Griffin, C. W., & Fricklas, R. L. (2006). Manual of low-slope roof systems. (4th ed.). New York: McGraw-Hill.